There are obviously many components that factor into a promotion decision. Oftentimes, the final decision comes down to simply timing and availability, but there are ways to make sure that you're the first person who comes to mind when your boss is considering who to promote. Presentations are a great opportunity to do just that. Here's how presentation skills improve your chances of promotion.
While all presentations don't involve leading others, every one is an opportunity to prove that you are a leader. How did you interact with the audience? Were people texting or whispering while you spoke? If so, how did you handle that? This is your chance to show that you can control a room, if need be.
A good presentation will have a well-defined roadmap at the beginning to help the audience follow along. Creating, and sticking to, a clear agenda will demonstrate to your boss that you're capable of organizing your ideas in a logical way.
This one is a no-brainer. However, I think that all too frequently confidence is confused with extraversion. Confidence isn't a desire to be the center of attention or an ability talk to random strangers. Real confidence is the result of being comfortable with who you are (super easy, right).
Not everyone is meant to be client facing and that is totally okay. Your presentation is your chance to show your boss that you can go to client meetings, events, and proposals. This obviously doesn't apply to everyone in the many industries and job types out there, but it can't hurt!
How well did you articulate your points? Did you vary your sentence structure and length? Were you able to make concise statements, or did you ramble and give unnecessary information/verbiage? This is incredibly important. If you're getting a promotion, you're likely going to be communicating with your boss more frequently than you are right now. If your boss doesn't want to communicate with you (because you take 20 minutes to say one thing), then s/he'll move forward with another candidate who won't waste her/his time.
With more responsibility comes more liability. What this means is that your behavior is scrutinized ever more granularly as you rise in the ranks (e.g. politicians). You need to prove that you won't be an embarrassment to both the company and the person giving you a promotion. Keep things professional (see my other post on Subjects to Avoid in a Business Setting if you're unsure what that entails) and your boss will be proud to promote you.